Reenforcement for tire beads



March 11, 1930. s, w ALDERFER 1,749,899

REENFORCEMENT FOR TIRE BEADS Filed April 5. 1927 INVENTOR,

ter/ingd//derfer .BY gy/@M ATTORNEY] STERLING W. ALDERFER, OF AKRON, OHIO, ASSIGNOR Patented Mar. 11, 1930 TO NATIONAL STANDARD COMPANY, OF NILES, MICHIGAN, A CORPORATION OF MICHIGAN REENFORCEMENT Application filed April 5,Y

This invention relates* broadly to` thev construction of inextensible tire beads such as vused in the manufacture of tires of the straight side or lin'extensible bead type. It

is directed more particularly to the design and construction of the metallic reenforcementused in the bead' of the tire' to impart the inextensibility to the bead. The object of the invention is to secure certain advantages in the manufactureof the bead as will be understood from the description of the invention as given below. j

A tire beadusually comprises a ring of Y rubber having embedded therein a plurality of wires which are ofl suiiicient strength and in suiicient numbers to give the required tensile strength to the bead. The bead may be given a preliminary` vulcanization so as to form it in a ring of substantially triangular form, before it is incorporated in the tire ory it may be incorporated in the tire structure in a green or unvulcanized s'tate, the complete curing and shaping of the bead .taking place when the tire is vulcanized. It is usu ally surroundedand encased in a fabric cover ing or jacket and is frequently associated with the so-called flipper strips which project outwardly from the bead, and are located between plies of the carcass.

For the reenforcing members' of the bead, at the present time, the materials used are either a braided wire tapel or a ywoven wire tape. The braided tape, which is the prevalent form, has a number. of objections, the principal one being that it is required to'be 'jmanufactured in machinery, which is expensi-ve to operate and maintain. The wires l 'constitnting the tape are braided and interlaced back and forth across the tape and breakage of the wire is quite frequent, requiring the use of wire of low tensile strength. The woven tape is also required to be formed upon Weaving machines, which increasev the cost of imanufac'ture; and in addition, the

crossing wire 'used to Vhold the lparallel or Warp wires in ixed relationship adds materially to the thickness of the wire tape and interferes with Athe subsequent rubberizing operation. j r

Either of' these forms of tape is required to FOR TIRE BEADS 1927. Serial No. 181,096. j,

be passed through a rubber extruding machine to receive a coating or casing or rubber 'before being 4wound into the grommet or ring which is subsequently lincorporated vin the bea-d, and this operation is often imperfect owing` to -t-he structure of the tape. Both forms of tape are rigid transversely and will not conform easily and readily to the finished formation required in beads, and this is particularly objectionable in the manufacture of tires with narrow beads such as required in the present popular drop center rim constructions.

but so far as known to me, the use of this type of bead has become practically extinct. I

j The form of bead reenforcement which constitutes the subject of this invention is much cheaper to manufacture andv obviates the objections which have been'noted above, and in addition. has certain advantages over Cable beads have also been used in the past t the old forms of reenforcement, as will be eX- n plained in the full description of the invention to follow. i

In ,the drawings which illustrate apreferred embodiment of the invention Fig;v 1 is a cross-section through a single 4 layer of the improved reenforcing material; Fig; 2 is a plan of a fragment thereof, the rubber being'removed from one end ofthe material to, disclose the arrangement of the Fig. 3 isa grommet lor ring made up from the material of Figs. 1 and 2 and in condition to be incorporated in the bead structure; v

Fig. 4 is a cross-section 'of a bead in the green or unvulcanized sta'te with a of fabric thereabout;

Fig. 5 is a cross-section ofa bead in the semi-cured condition; and

Fig. 6 is a detail of a tire bead having the improved bead embodied therein.- I

The' r^eenforcing material consists of a plurality of vparallel wires 2 which are arranged in a single plane and in close proximit to one another. Any suitable number of t ese wires may be employed in a single length of the material. These wires are not interlaced covering 'or interwoven but are held together solely by a rubber covering or jacket 3 which completely encloses the Wires and penetrates into the crevices or interstices between the Wires. The Wires are held and maintained in posi- Ition solely by the rubber jacket or casing tape form lsolely by the rubber coating and jacket surrounding them. The reenforcement may be termed as a rubber tape having parallel Wires embedded therein. As there is no braiding or Weaving operation, the Wires may be of a greater tensile strength thanthe Wires in the tape heretofore used.

A length of the tape 4 is wound into ring form in a plurality of convolutions suticient to afford the requisite number of Wires as required by the demands of the tire in which it is to be incorporated. A ring or grommet G made in this manner is illustrated in Fig. 3. The end of the grommet may be retained in place by the sticky rubber coating, or an additional securing means may be provided, a metallic staple 7 being illustrated for this purpose.

Thering of Fig. 3 is usually covered with a fabric Wrapper 8 (Fig. 4) and may be incorporated in the tire in this form, the bead being known, in the art as a green bead which is completely cured With the tire casing. This form of bead is quite usual in the manufacture of t-Qes by the flat band or drum built method.

Tn some cases, it is preferable to give the bead a preliminary or partial vulcanization to shape it into substantially triangular crosssection, and this form of bead is illustrated in Fig. 5. l

A complete tire bead is shoWI-rn Fig. 6, in Which the bead is shown occupying its final position in the completely cured tire.

In the vulcanizat-ion of the bead either cornpletelywithin the tire Vor partially in bea-d form, the bead is deformed somewhat by the congurationof the mold cavity. The improved form of bead isparticularly adaptable for this operation, the several Wires being un# connected, except for the rubber, may'shift or change their position as required' by the vulcanizing process more easily than the Wire tape ofthe previous combination in which the movement of the Wires is restricted and retarded bythe tape formations. During the vulcanizing process the rubber is softened and will permit the wires to arrange themselves in the bead more readily in the improved form than in the prior forms of bead reenforcement. v

It will be observed that the rubber surrounding the wires operates as a temporary holding medium for maintaining the Wires in parallel relationship, but that on the vulcanization of the bead, the rubber softens and forms the body of the bead, the Wires being free to locate themselves in their most natural position Without tension or stresses therein. The rubber casing thus serves the function of holding the Wires in ribbon or tape form until the vulcanizing operation.

Other advantages are obtained by the improvement herein described and claimed, as will be apparent to those skilled in the art. This application is a continuation in part of application Serial No. 90,324, filed February 24, 1926. The claim is intended to cover the invention as broadly as the limitations of the prior art will permit, and within a fair interpretation of the claim.

' That is claimed is:

A bead construction vfor pneumatic tires comprising a body of rubber, and a reenforcement comprising a plurality of independent parallel, longitudinal Wires embedded therein and unconnected except for the rubber, each of said Wires being arranged in a plurality of spaced convolutions about the bead.

STERLING W. ALDERFER. 

